在Android上简单导出和导入SQLite数据库
我想实现一个简单的SQLite导出/导入用于备份的目的。 导出只是存储原始current.db文件的副本。 我想要做的导入就是删除旧的current.db文件，并将imported.db文件重命名为current.db 。 这可能吗？ 当我尝试这个解决scheme时，我得到以下错误：
06-30 13:33:38.831: ERROR/SQLiteOpenHelper(23570): android.database.sqlite.SQLiteDatabaseCorruptException: error code 11: database disk image is malformed
如果我在SQLite浏览器中查看原始数据库文件，它看起来很好。
我在其中一个应用程序的SQLiteOpenHelper中使用此代码来导入数据库文件。
编辑：我粘贴我的FileUtils.copyFile()方法到问题中。
SQLiteOpenHelper
public static String DB_FILEPATH = "/data/data/{package_name}/databases/database.db"; /** * Copies the database file at the specified location over the current * internal application database. * */ public boolean importDatabase(String dbPath) throws IOException { // Close the SQLiteOpenHelper so it will commit the created empty // database to internal storage. close(); File newDb = new File(dbPath); File oldDb = new File(DB_FILEPATH); if (newDb.exists()) { FileUtils.copyFile(new FileInputStream(newDb), new FileOutputStream(oldDb)); // Access the copied database so SQLiteHelper will cache it and mark // it as created. getWritableDatabase().close(); return true; } return false; }
文件实用程序
public class FileUtils { /** * Creates the specified <code>toFile</code> as a byte for byte copy of the * <code>fromFile</code>. If <code>toFile</code> already exists, then it * will be replaced with a copy of <code>fromFile</code>. The name and path * of <code>toFile</code> will be that of <code>toFile</code>.<br/> * <br/> * <i> Note: <code>fromFile</code> and <code>toFile</code> will be closed by * this function.</i> * * @param fromFile * - FileInputStream for the file to copy from. * @param toFile * - FileInputStream for the file to copy to. */ public static void copyFile(FileInputStream fromFile, FileOutputStream toFile) throws IOException { FileChannel fromChannel = null; FileChannel toChannel = null; try { fromChannel = fromFile.getChannel(); toChannel = toFile.getChannel(); fromChannel.transferTo(0, fromChannel.size(), toChannel); } finally { try { if (fromChannel != null) { fromChannel.close(); } } finally { if (toChannel != null) { toChannel.close(); } } } } }
如有必要，不要忘记删除旧的数据库文件。
这是一个简单的方法将数据库导出到一个名为backup文件夹的文件夹，您可以根据需要命名该文件夹，并使用一个简单的方法从相同的文件夹导入数据库
public class ExportImportDB extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); //creating a new folder for the database to be backuped to File direct = new File(Environment.getExternalStorageDirectory() + "/Exam Creator"); if(!direct.exists()) { if(direct.mkdir()) { //directory is created; } } exportDB(); importDB(); } //importing database private void importDB() { // TODO Auto-generated method stub try { File sd = Environment.getExternalStorageDirectory(); File data = Environment.getDataDirectory(); if (sd.canWrite()) { String currentDBPath= "//data//" + "PackageName" + "//databases//" + "DatabaseName"; String backupDBPath = "/BackupFolder/DatabaseName"; File backupDB= new File(data, currentDBPath); File currentDB = new File(sd, backupDBPath); FileChannel src = new FileInputStream(currentDB).getChannel(); FileChannel dst = new FileOutputStream(backupDB).getChannel(); dst.transferFrom(src, 0, src.size()); src.close(); dst.close(); Toast.makeText(getBaseContext(), backupDB.toString(), Toast.LENGTH_LONG).show(); } } catch (Exception e) { Toast.makeText(getBaseContext(), e.toString(), Toast.LENGTH_LONG) .show(); } } //exporting database private void exportDB() { // TODO Auto-generated method stub try { File sd = Environment.getExternalStorageDirectory(); File data = Environment.getDataDirectory(); if (sd.canWrite()) { String currentDBPath= "//data//" + "PackageName" + "//databases//" + "DatabaseName"; String backupDBPath = "/BackupFolder/DatabaseName"; File currentDB = new File(data, currentDBPath); File backupDB = new File(sd, backupDBPath); FileChannel src = new FileInputStream(currentDB).getChannel(); FileChannel dst = new FileOutputStream(backupDB).getChannel(); dst.transferFrom(src, 0, src.size()); src.close(); dst.close(); Toast.makeText(getBaseContext(), backupDB.toString(), Toast.LENGTH_LONG).show(); } } catch (Exception e) { Toast.makeText(getBaseContext(), e.toString(), Toast.LENGTH_LONG) .show(); } } }
不要忘记添加这个权限来继续
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" > </uses-permission>
请享用
